1. Field
The invention relates generally to the field of telecommunications, and more specifically to mechanisms for detecting and evaluating packets and frame transmissions in a wireless communication system having multiple channels with varying channel qualities.
2. Background
Wireless communication technologies are rapidly advancing, and wireless communication systems are utilized to provide a larger and larger portion of the communications capacity that is currently available to users. This is true despite the additional technological impediments that are faced in implementing a wireless communication system, as compared to a wireline system. For instance, wireless communication systems must deal with issues relating to data transmission between a base station and its mobile stations in order to maximize the performance of the system, whereas a wireline system does not.
One type of wireless communication system comprises a cellular CDMA2000 (code division multiple access) system which is configured to support voice and data communications. This system may have multiple base stations which communicate via wireless channels with multiple mobile stations. (The base stations are also typically coupled via wireline networks to various other systems, such as a public switched telephone network.) Each base station communicates with a set of mobile stations that are within a sector corresponding to the base station. This base station is responsible for detecting errors in transmissions from the mobile station in order to properly demodulate and decode the signal from the mobile stations in addition to controlling power in communications between the base station and the mobile stations in order to minimize interference and maximize throughput, as well as enabling the mobile stations to conserve energy and thereby extend the amount of time during which they can be used.
Typically, a cyclical redundancy check (CRC) is utilized to detect errors in transmissions from the mobile stations. Ideally, transmissions are divided into predetermined lengths and divided by a fixed divisor. The remainder number from this division operation is then appended onto the transmission by the mobile station. Upon receiving the transmission, the base station recalculates the remainder and compares it to the received remainder. If the two remainders do not match, the base station has detected an error in the transmission.
This method for error detection, however, may not be feasible for certain types of transmission channels. Burst oriented data transmission channels may have a corresponding rate indicator channel which signals a base station of the transmit format of the burst oriented channel and drives the power control loop. While a CRC may allow error detection in data transmissions, in systems having channels which transmit sporadically and are burst oriented the overhead for utilizing a CRC on their corresponding rate indicator channel may be too high. In most cases, a CRC requires 8 to 10 bits to be appended to each data transmission, however, on a rate indicator channel a transmission itself may only consist of a few bits at a time. The transmission of these added CRC bits increases transmission power significantly. This is problematic, however, as the base station still requires high probability identification of good and bad frames on this rate indicator channel in order to detect the transmit format of these enhanced channels and for adjustment of the power control loop.
There is therefore a need in the art for systems and methods which allow identification of packets on a rate indicator channel, and the high probability identification of good and bad frames on the rate indicator channel and the corresponding spontaneous data transmission channel.